Power unit for bicycles



May 15, 1951 H. H. DINKINS, JR

POWER UNIT FOR BICYCLES Filed Feb. 25, 1948 lNVEN TOR H. lhrzirzm;

ATTORNEYS Hnry Patented May 15, 1951 UNITED STATES PATENT oFFIcE' POWER UNIT FOR BICYCLES Henry H. Dinkins, Jr., Harrison, N. Y.

Application February 25, 1948, Serial No. 10,623

4 Claims.

The present invention relates to a new and improved power unit particularly adapted for the self-propulsion of bicycles.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

Of the drawings:

Figure 1 is a side elevation of a bicycle having power unit attached thereto; and

Figure 2 is a fragmentary plan view of the parts shown in Figure l.

The present invention has for its object the provision of a novel and improved power unit for bicycles which is easily attached to and detached from the bicycle and which gives a more stable ride than is usual with devices of the prior art. A further object is the provision of a power unit which does not interfere with the steering of the bicycle which requires only a single control for its operation and which follows closely the normal path of the rear bicycle wheel. Still another object is the provision of a self-propelled wheeled unit which is provided with connecting means by which the power is applied from behind and in line with the bicycle during normal straight travel and serves to help steer the bicycle on turns.

As embodied, the power unit comprises a frame having a single wheel driven from a prime mover under control of the rider and preferably through speed responsive clutch means, so that the prime mover is automatically disconnected when its speed is reduced. The Wheel is preferably near the rear of the frame, the frame is low enough so that its center of gravity is approximately in line with or below the axes of the bicycle wheels and the frame is connected at its front end to a member fixed with reference to the bicycle frame adjacent the rear edge of the rear wheel and horizontally alined with or below the bicycle wheel axis and in the same vertical plane as the rear wheel. This connection may be a universal joint, but preferably has Only two degrees of freedom, about a horizontal transverse axis and a substantially vertical axis. The distance from the connecting joint to the unit wheel is preferably from 1% to 1% times the distance from the connection to the rear bicycle wheel axis, so as to cause the unit wheel to track closely with the rear bicycle wheel on normal turns as well as during straight riding, thereby adding to the stability of the ride and reducing the power required in heavy going such as light snow, mud, gravel or sand. I

It will be understood that the foregoing general description and the following detailed description as well are exemplary and explanatory of the invention but are not restrictive thereof. Referring now in detail to the preferred and illustrative embodiment shown in the accompanying drawings, the bicycle comprises a conventional bicycle having a frame III, a steering fork [2, front wheel [4, rear wheel l6 withcoaster brake l8, handle bars 20, seat post clamp 22 and pedals 24.

The power unit comprises a frame bent from a metal tube or otherwise fabricated and providing a horizontal bed 26 with a rounded rear portion 28 and upbent ends 3|]. On the bed, near a tired wheel 4|, is mounted a small internal combustion motor 40, generally a gasoline motor of from 1 to 3 horsepower while near the rear end and between the parallel horizontal reaches of the bed 26 is mounted the tired wheel 4|, journalled in bearings 42 by shaft 43 on which is connected a V-belt pulley 44. Above wheel 4|- is a jack shaft 45 journalled in adjustable bearings 46 which are supported on journals 42.

Shaft 45 has a large V-belt pulley 41 and a. small V-belt pulley 48, pulley 41 being driven from the motor 40 by pulley 49 on the motor shaft through belt 5|, while pulley 48 drives pulley 44 through belt 50, forming a reduction drive from the motor 46 to the wheel 4|.

For more easily controlling the power unit, motor pulley 49 is a clutch, and preferably a centrifugal clutch, engaging when the motor is speeded up substantially above idling speeds. Thus the operator need only control the motor speed, and no separate clutching and declutching operation is needed.

The power unit is connected to the rear of the bicycle and in line with the bicycle frame I 0 by means of an articulated joint providing a transverse pivotal axis and a vertical pivotal axis rigidly connected just behind the rear bicycle wheel l6 and preferably slightly below the axis of the coaster brake [8. The rigid fixed connection with the bicycle is provided by means of a braced frame connected to the bicycle seat post clamp 22 and the coaster brake axis. The braced frame comprises two members 66 and 61 at each side of the wheel I6 and joined together by a cross member 68, the lengths of the members 66 and 61 being such that the member 68 is located just behind the wheel l6 and at the level of or slightly below the axis of brake 18. The upper? endsofmember 6T." are? fastened by the tighteningbolt 69*for the seat post, while the forward ends of the members 66 are secured by the usual nuts at the ends of the coaster" is an articulated connection having-at'least two degrees of freedom, one about a horizontalaxis.

the other about a vertical axis forming a thrust transmitting connection from the power unit to the bicycle. As embodied, a bracket Ill joins the ends- 30. of the frame and: supports a 1 trans-' Verse horizontal axis" 12- whilea bracket. M is securedr'to'the: cross mernber 68 and supports the vertical. axis? 16.= The-axes-' 12 and 16 may' Ice-formed as: an integral cruciform piecehaving cap'screws:threadeddntomhe ends of each arm.-

Eorcontrolling. thespeed and power output of4themotor 40,- a -push pullcontrolBd is connected. to the throttle. and. may be manually actuated by a manualcontrol member 82 mounted'on the handlebar 20..

Breferably when the'power unit is used with atconventionalbicycle-having twenty-eight inch wheelsand aspacing; of:- about forty-one inches between the frontt-a-ndx rear wheels on the-road, the articulated connection: islocated: some sixteen inehes'behind themOastBr brakeshaft; while the. power-Junie wheel. engages the road from inches to. twentyeight inches. behind the articulated: connection. The center. of gravity ofthe powerunitisat-least as low-as. the shaft l8, and the weight distribution of. the power unit is: such-sthatl only about. one-third of its weight. is: applied to? the articulated connection; whilethel-lever ratio between the articulated con neotionrandithe'roa'dtengaging point-of the front wheel ,with the'shaft- I8 considered as the fulcrum. I is about -1@ to a 3; thereby applying only about.- tol iandpreferably A ofthe-weight of the-power unittending. to.- Iift'thefrontwheel fronrthez-ground. Thus there is given sufficient pressure. forgood: steering; v and stability while the bicycle is-standingatwrest and unmounted.-

. 'I'he distancesbetweenshaft N3; the" road en-' gaging point of the wheel 4| and the articulated joint insure close tracking of the wheels 4| and I6 when turning normally.

Also, when turning to one side, the articulated joint is oppositely moved causing the thrust of motor to be applied to assist in the turn.

The invention in its broader aspects is not limited to the specific mechanisms shown and described but departures may be made therefrom: within the scope of the accompanying claims without departing from the" principles of the invention and without sacrificing its chief advantages.

' Whatvisclaimed is:

1. A power unit for bicycles including in combinationa frame having a single road wheel near itsrearv end-thereof, an articulated connection at its front end, a prime mover on the frame positioned between said road wheel and said connection connected to drive the wheel, and a second frame connected tothearticulated connection,.and:bracing means extending angularly from said second frame from a point' adjacent the" articulated connection, said second frame and said bracing means connectable'with a bicycle at vertically spaced pointson thebicycle frame to"- fiX the articulated connection behind the'rear'bicycle' wheel and not above: its axis.

2. A powerunit as claimed'in'claim l in which the articulated connection is directly behind the rearbicyclef Wheel and provides a transverse and? a* vertical axis of pivotal movement.

3. A powerunit' as claimed in cl'aim.2iin which the articulatedjoint is spaced from the road engagement of'the unit wheel from' 1 ,v col times as far as from" the road. engagement of the'rear bicycle wheel;

4. A power unit as claimed is claim'3 in which the center of gravity of the unit islower than the. rear-"bicycle wheel axle:

H-ENRYTH'. DINKINS, JR.

REFERENCES" CITED The following references are of record in the file of'this patent:

V UNITED STATES PATENTS 

